Adapters

Nix.js Kit includes built-in adapters for the most common deployment platforms. Each adapter generates a self-contained server entry that serves static files and renders pages on demand.

# Vercel

nix-js-kit build
nix-js-kit adapter vercel

Produces a .vercel/output directory compatible with the Vercel Build Output API v3:

• static/ — static files from dist/
• functions/__nix-js-kit.func/index.js — bundled SSR function
• config.json — routing configuration

Programmatic usage:

import { vercelAdapter } from "@deijose/nix-js-kit/adapters/vercel";

await vercelAdapter.build({
  root: process.cwd(),
  appDir: "src/app",
  islandsDir: "src/islands",
  outDir: "dist",
  clientEntry: "/_nix-js/entry-client.js",
  lang: "en",
});

# Netlify

nix-js-kit build
nix-js-kit adapter netlify

Produces:

• netlify/functions/__nix-js-kit.mjs — bundled SSR function (Netlify Functions v2)
• netlify.toml — redirects unmatched routes to the function

Static files stay in dist/ and are served directly by Netlify.

import { netlifyAdapter } from "@deijose/nix-js-kit/adapters/netlify";

await netlifyAdapter.build({
  root: process.cwd(),
  appDir: "src/app",
  islandsDir: "src/islands",
  outDir: "dist",
  clientEntry: "/_nix-js/entry-client.js",
  lang: "en",
});

# Bun

nix-js-kit build
nix-js-kit adapter bun
bun run .nix-js/bun-server.ts

Generates:

• .nix-js/bun-index.ts — SSR handler entry
• .nix-js/bun-server.ts — Bun server serving dist/ and rendering pages

The server respects the PORT environment variable (default 3000).

import { bunAdapter } from "@deijose/nix-js-kit/adapters/bun";

await bunAdapter.build({
  root: process.cwd(),
  appDir: "src/app",
  islandsDir: "src/islands",
  outDir: "dist",
  clientEntry: "/_nix-js/entry-client.js",
  lang: "en",
});

# Node

nix-js-kit build
nix-js-kit adapter node
node .nix-js/node-server.mjs

Generates a single bundled .nix-js/node-server.mjs that serves dist/ and renders pages on demand. Requires Node 18+.

The server respects the PORT environment variable (default 3000).

import { nodeAdapter } from "@deijose/nix-js-kit/adapters/node";

await nodeAdapter.build({
  root: process.cwd(),
  appDir: "src/app",
  islandsDir: "src/islands",
  outDir: "dist",
  clientEntry: "/_nix-js/entry-client.js",
  lang: "en",
});

# Custom adapter

You can build a custom adapter using the shared adapter helpers:

import type { Adapter, AdapterOptions } from "@deijose/nix-js-kit";

const myAdapter: Adapter = {
  async build(options: AdapterOptions) {
    // 1. Build the SSR entry
    // 2. Bundle it for your platform
    // 3. Generate platform-specific config files
  },
};

# What adapters do

All adapters share the same pattern:

1. Bundle the SSR entry — embeds the full route table, no runtime filesystem scanning
2. Include layout.data.ts modules in the registry
3. Preserve action resolution by page scope
4. Serve the /__nix-js/render endpoint (HTML or JSON) for SPA navigation
5. Forward cookies to API routes and server actions
6. Render custom error pages (404, 500)
7. Run middleware if src/middleware.ts exists
8. Declare adapter capabilities — each host declares an AdapterCapabilities object so the framework knows which features are safe to enable (streaming, filesystem, image runtime, background work). See Adapter Capabilities.

# Unified Web handler

Since v2.0.2, every runtime path — dev, preview, start, and all four adapters — funnels through a single createWebHandler() function. This means:

• No duplicated logic between dev, preview, and production adapters.
• Identical behavior for actions, API routes, static serving, SSR, error pages, and the render endpoint across all runtimes.
• One place to fix bugs — a fix in createWebHandler applies everywhere.

import { createWebHandler } from "@deijose/nix-js-kit/runtime";

const handler = createWebHandler(routes, actions, {
  staticRoot: "./dist",
  lang: "en",
  clientEntry: "/_nix-js/entry-client.js",
  securityHeaders: true,
});

// Use with any Web-standard runtime
const response = await handler(request);

See Unified Web Handler for the full API.